Many industrial processes require the melting of large quantities of solid material and the maintenance of the resulting melted fluid at a uniform temperature and uniform consistency.
The present invention relates to the melting of pitch and the like which is later used in the molten state. Pitch has heretofore been melted in a large container to which heat was supplied and new solid pitch added as molten pitch is withdrawn. This, however, has inherent disadvantages.
Pitch contains a substantial portion of water which is driven off by the melting temperature of between about 180.degree. and 200.degree. C. When new pitch is added at the top of the large container, the process of driving off the water causes local cooling and lumps in the vicinity of the fresh pitch. Consequently, non-uniform temperature and lumps are formed in the melted material which frequently remain for long enough to be drawn from the tank into the using process, a highly undesirable result. Many industrial processes also include the melting of solid materials and are hampered with lumpy and/or variable temperature melted material. The present invention can be used also in these processes.